Many of the devices in today's electronics are passive components such as resistors, inductors, and capacitors. For size, cost, and performance reasons, the passive components are commonly integrated onto a substrate and packaged with other passive components, as well as with active components.
Passive devices may be subject to performance degradation or failure in the event of moisture intrusion. If moisture penetrates the space between the top and bottom metal plates of a capacitor, for example, a leakage path may result. Moisture intrusion may be experienced by various types of packages, but non-hermetic packages may be particularly susceptible, in that the integrated capacitor may be directly exposed to a humid environment. High operating voltage and poor adhesion between metal and protective overcoat may further increase the likelihood of moisture-related failures.